The Hong Kong government has ignored a warning from Washington about letting an oil tanker carrying petroleum from Iran stop in the city.

Hong Kong’s Commerce and Economic Development Bureau said that other than sanctions endorsed and promulgated by the United Nations Security Council which Hong Kong had always abided by, the city did not have any obligation to execute US sanctions against another country.

The UN had not imposed any restrictions on the export of petroleum from Iran, said the bureau.

“Certain countries may impose unilateral sanctions against certain places on the basis of their own considerations. Those sanctions are outside the scope of the UN Security Council sanctions implemented by the Hong Kong government,” read a statement.

The bureau added that it had always consulted the Chinese foreign ministry on enforcing UN sanctions against Iran.

It is understood that the US Consulate General in Hong Kong approached local officials on Wednesday and warned that the city must not offer any services to any vessels carrying goods from countries sanctioned by the US. A tanker, the Pacific Bravo, fully laden with Iranian oil, was believed to be en route to the city.

The tanker is owned by China’s Bank of Kunlun, a China National Petroleum Corp (PetroChina) subsidiary also sanctioned by the US in 2012 for acting as the main conduit for deals with the Islamic Republic.

The bank has since switched to Euro and Chinese yuan to settle its payments. China is a top buyer of Iranian oil and nearly all its oil payments go through the bank.

Also some reports, including those by Reuters and Bloomberg, noted that the tanker had changed course to skip its original destination of Indonesia on Monday and docked in Sri Lanka instead. It had then set sail again on its way to the Strait of Malacca, likely to East Asia.

Hong Kong’s Marine Department said on Wednesday evening that it “has no information showing if the respective vessel will enter or pass by Hong Kong waters.”

Ship-tracking website Marine Traffic shows the oil tanker Pacific Bravo (red arrow) is now off Sri Lanka, likely en route to the Strait of Malacca, with its destination still set as Indonesia.

In April, US President Donald Trump stepped up measures to cut off Tehran’s oil exports – pillars of the country’s foreign exchange reserves – and scrapped waivers granted to key buyers including China, which has shrugged off US sanctions all along.

Washington reinstated sanctions against Iran’s oil industry in November, but allowed some buyers limited purchase quotas under a waiver program that expired on May 1.